Modern production lines, in which multiple operations are performed at separated stations to produce a finished article, require conveyors to advance the work piece or product from one station to another. Conveyors carry the product as it is produced or assembled, and then carry the product for packaging and eventual discharge to storage or a shipping point. To most effectively make use of production floor space, it is often desirable to cause the product to turn a corner or to reverse its direction of travel. The conveyor corner turn enables the product to negotiate a change in direction up to a full 180 degree turn or to spiral upward to change heights.
Without being very costly or unsanitary, the conventional wide belts on a belt conveyor are not able to make a turn without undesirable wrinkling or displacement of the belt. Plastic or metal link conveyor belts are collapsible at the inner radius to allow a curved path, but such belting material is costly and, because of the multiple cavities defined between the links, difficult to clean.
Ease of maintenance and cleaning is important in conveyors, and is particularly so in food product applications. Health and safety regulations set standards for cleanliness which must be maintained when food products are being manufactured, packaged and transported.
Conveyors are known which employ plural, generally parallel arrangements of rubber belts which are supported on metal tables, and which make a turn by angling around rotatable pulleys mounted to the table. Such older design conveyors are generally not cleanable by current USDA standards. In addition, conveyors employing rubber belts required that the mechanism allow a belt to be installed as a preformed loop, necessitating many release catches and fasteners which are potential sites for dirt accumulation. Conveyors employing flexible urethane belting of circular cross-section have also been used. Urethane belting is particularly suited to hygienic uses because it has a smooth moisture-resistant surface which may be easily cleaned. Although flexible urethane belting may be mounted on the conveyor by welding of cut belt ends, the welding operation does require set-up and cooling time, and a certain amount of skill is required from the belt installer. Another known conveyor loops the flexible urethane belts around pulleys which are arrayed on radial arms which cut across the conveyance path and returns the belts on an underlying array of return pulleys. Such systems, however, require welding of the belts to install them on the machine, and utilize the resilience of the urethane belting to properly achieve tension on the belts. Resilient urethane belts are stretchable, and hence will deflect downwardly as the conveyed article is supported. If the conveyed article is of too great a weight, proper belt travel may be impeded.
Typically smaller articles have had to be conveyed around corners on multiple contacting rollers, specialized expanding link belts or other complex and costly conveyor systems. Complicated linked belt systems will often present greater difficulties in cleaning due to the number of linked parts.
What is needed is a hygienic conveyor corner turn which can support moderate to heavy products as well as smaller discrete articles and which minimizes down time by rapid changeover of new belts.